How to Select Multicore Cables

Conductor Selection

There are three kinds of applications:

• Low level Signal transmission e.g. sensor wire: Mechanical strength is of prime consideration over resistance. To minimize weight where mechanical strength is not required some of our customers have used a twisted shielded pair of AWG 34 conductors.
• Power transmission e.g. motor drive cables: Resistance of the wire is the basis for conductor selection (see our conductor table fir resistance). For certain high power transmission we can provide wires of sizes up to AWG 4
• Signal transmission over a long distance where attenuation is important: Larger gauge offers lower attenuation

Insulation Selection

Insulation is governed by working voltage, mechanical protection and capacitance. The standard insulations are ET (250 V AC), E (600 V AC), EE (1000 V AC).

Another popular albeit non standard insulation is ET+ (thickness 0.175 mm or 7 mil) which offers additional protection against incidental damage.

The most common insulation in multi core cables is Type E (600 V AC) with a minimum insulation thickness of 0.25 mm (10 mils).

For higher working voltage applications, insulation ratings of Type EE, X1.5 CR, X3.0 CR etc. can be specified. (link to HVCR cables)

Thicker insulation offers lower capacitance within a pair and between pairs.

Isolation and Shielding Requirement

Twisted pairs offer an inherent protection against electrical interference (EMI) due to the balanced signal transmission. Their shielding offers additional isolation in the most sensitive applications. In situations requiring extreme isolation double shields are also specified. We can add drain wire under the shield for ease of termination.

We offer three types of shield

• Foil Shieldâ€?minimum addition to outer diameter but less flexible than round wire
• Round Wire Braided Shield â€?used in 98% applications. It offers excellent coverage (ranging from 85% to 95%), flexibility, ruggedness and flex life.
• Served Shield â€?Helically wrapped Strands of round wire in a single direction. Their contribution to diameter is medium but the coverage detoriates over life of equipment if repeated flexing is encountered.

Cross talk requirements: Near End Cross Talk (NEXT) & Far End Cross Talk (FEXT)

Cable construction method including Twisting pattern and placement of wires affect the cross-talk performance. We maintain quality control to assure consistence performance.

Mechanical considerations e.g. flex life, dimensions

Thicker cables with more wires and multiple shields become less flexible. Outer jacket (sheath) ranges from 0.2 mm to 0.6 mm depending on the outer diameter (OD) of the cable.

Working Environment

PTFE jacket provides protection under corrosive and harsh environment but a poly urethane jacket can be specified for applications encountering mechanical abrasion.

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